Atomizing apparatus for finely distributing a liquid in an air stream

ABSTRACT

An apparatus is disclosed for efficiently atomizing and finely distributing a liquid in an air stream, for extracting maximum benefit from the liquid for the intended use, which may be for combustion as in jets and combustion chambers for gas turbines, or for moisturizing equipment, or for use in the chemical industry, for example, where the liquid will be suitable for the purpose intended, as for extraction of heat energy, or for mixing purposes, or the like.

United States Patent [1 1 Singh Nov. 4, 1975 [54] ATOMIZING APPARATUSFOR FINELY 3,254,846 6/1966 Schreter et al. 239/400 IST UT A LIQUID INAN AIR 3,483,699 12/1969 Harvey 60/39.74 R STREAM 3,530,667 9/1970 Bryan60/39.74 R 3,713,588 1/1973 Sharpe 239/400 [75] Inventor: RitindarSingh, Finspong, Sweden [73] Assignee: Stal-Lavel Turbin AB, Finspang, aE i j h Love Sweden Attorney, Agent, 0r FirmEric Y. Munson [22] Filed:Sept. 26, 1974 [21] Appl. No.2 509,492

. 57 ABSTRACT Related US. Application Data [63] Continuation of Ser. No.352,542, April 19, 1973, An apparatus is disclosed for efficientlyatomizing and abandoned. finely distributing a liquid in an air stream,for extracting maximum benefit from the liquid for the intended [52] US.Cl. 239/400; 239/404; 239/406; use, which may be for combustion as injets and com- 239/430 bustion chambers for gas turbines, or formoisturizing [51] Int. Cl. B05B 7/00 equipment, or for use in thechemical industry, for ex- [58] Field of Search 239/400, 403-406, ample,where the liquid will be suitable for the pur- 239/424.5, 425, 429, 430,431, 433, 434, pose intended, as for extraction of heat energy, or for434.5; 60/39.74 R mixing purposes, or the like.

[ References Cited 7 Claims, 3 Drawing Figures UNITED STATES PATENTS2,539,314 1/1951 Murphy 239/404 x l5 I6 7 I! I I I I0 US. Patent N0v.4,1975 3,917,173

ATOMIZING APPARATUS FOR FINELY DISTRIBUTING A LIQUID IN AN AIR STREAMThis is a continuation of application Ser. No.

352,542, filed Apr. 19, 1973, now abandoned.

BACKGROUND OF THE INVENTION This invention is directed to an atomizingstructure, which serves to provide a fine distribution of liquid forintroduction into an air stream driven past the apparatus; whichstructure functions to provide a high degree of atomization of theliquid and consequent optimum mixing with the air stream. The apparatusembodies a primary or basic hollow cylinder with a hollow wall chamberfor receiving a liquid, that passes through perforations in the innerwall of the chamber into thin layers onto the surface of the cylinder.The perforations are disposed in a direction as near as possible to thetangential to the inner surface of the cylinder, in order to embodysharp edges, that will tend to reduce the thickness of the liquid layerat those edges and will stimulate the formation of small droplets formaximum efficiency in mixing the liquid and air stream.

OBJECTS OF THE INVENTION The primary object of this invention is toprovide a fluid distributor, for use in and with a moving air stream,that will provide a highly effective and efficient atomization of thefluid for optimum and highly efficient mixing of the fluid in a finelydivided state in the air stream.

Another object of the invention is to provide a fluid distributor thatmay be easily enlarged in sectional area dimensions to take care oftreating air streams of increased dimensions.

Another object of the invention is to provide a liquid atomizingdistributor, that is simple in construction and economical tomanufacture.

A further object is to provide such a structure for atomizing anddistributing a fluid into an air stream, that is highly efficient inestablishing a good mixing action between the fluid and the air stream.

Another object of the invention is to provide a simple liquiddistributor of simple construction, free of moving parts, and serving toachieve maximum atomization of liquid into an air stream, by creating ahigh degree of turbulence in the air stream, in such manner as toestablish a high degree of wiping action of the air stream on thesurfaces of the distributor by such turbulence, during the passage ofthe air stream past and through the liquid distributor.

SUMMARY OF THE INVENTION This invention relates to an atomizing systemfor finely distributing a liquid in an air stream.

There are many applications where it is desired to atomize a combustibleliquid in an air stream for optimum combustion and extraction of energyfor many utilitarian purposes. Such a system is used, for example, injets and combustion chambers for gas turbines, and in oil-fired boilers,and can also be used in drying equipment, or moisturizing equipment inthe chemical industry, for example. In accordance with this invention,apparatus of the type disclosed herein is suitable to permit largequantities of air to be extracted to take up correspondingly largequantities of finely distributed atomized liquid.

In conventional apparatus for this atomizing purpose, generally one ormore nozzles have been used to project a conical or annular jet ofliquid out into the air stream. Atomization of the liquid is achieved byexpressing liquid out through fine apertures or gaps in the nozzle, andthe quantity of liquid that can be thus ejected from a nozzle isextremely limited. If larger quantities are required, the number ofnozzles may be increased, but that is in itself a complication just asthe individual nozzles are rather complicated.

The present invention uses considerably simpler basic components topermit liquid to be mixed into air streams of unlimited magnitude. Thebasic element according to the invention is a tubular surface, which maybe cylindrical or conical, and which is disposed in the path of the airstream, i.e. parallel, coaxial or concentric with such path, so that theair stream flows over and sweeps the surfaces of the basic elements formaximum intermingling activity. The liquid is flowed out onto thosesurfaces and is even further distributed over those surfaces by the airstream, which is controlled to be turbulent to achieve maximum atomizingand mixing, after which the atomized liquid leaves the surfaces in thedirection of the air stream in the form of a finely distributed veil atthe edge of the surface, thereafter becoming mixed with the air stream.By arranging several such surfaces concentrically or coaxially with eachother and the air stream, it is in principle possible to opy erate withair streams of any size, and, by varying the spacing between thesesurfaces, the desired concentration of liquid in the air stream can beobtained with maximum efficiency of the atomization.

The basic element is constructed as a hollow doublewalled cylindrical,or conical, tubular ring, which serves as distributor of the liquid. Achamber is formed between the walls of that distributor, and isconnected to the liquid supply, suitably via a pressure pump. Holesdrilled through the inner wall of the ring, preferably almost tangentialto the inner surface of the distributor, serve as passages through whichliquid is laid out as a film on the inner surface.

By surrounding the first ring with an extra ring, the fine holes on theoutside of the first ring direct a spray onto the second ring so anextra distribution surface is obtained for the liquid and, as will beseen in the following, it is possible to continue in this way, thusincreasing the system to an arbitrary cross section, according to thedimension of the air stream desired.

The atomizer apparatus according to the invention is described in thefollowing specification, with reference to the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 shows an atomizing distributoraccording to the invention; and

FIG. 2 shows how such a structure can be extended.

FIG. 3 is a fragmentary section of the distributor shown in FIG. 1.

DETAILED DESCRIPTION OF A PREFERRED EMBODIMENT FIG. 1 shows an atomizingapparatus according to the invention, for use in, for example, an oilburner for a gas turbine, or for a steam boiler. The air stream isproduced by a compressor or fan 1 in the casing 2, and the air streamthen continues through the atomizing device or distributor 3. Thedistributor consists here of a 3 basic cylindrical element 4, and anextra cylinder ring 5 surrounding the inner cylindrical ring 4.

The basic cylindrical element 4 consists of a ring which may becylindrical, as shown, or it may converge forwardly to be conical. It isplaced with its axis parallel to the air stream. The ring 4 is hollowand has an internal chamber 6 to which liquid is supplied through atleast one tube 7, for distribution into the air stream. The chamberwalls are provided with drilled holes 8, through which the liquid issprayed out. These drilled holes are preferably directed obliquely, withrespect to the radii of the ring. The obliquely drilled holes aredisposed to be substantially tangential to the inner surface 9 of thering. It is thus ensured that the liquid is distributed immediately overthe inner surface 9 instead of streaming out solely freely into thecentre of the ring, with the risk of larger drops being carried out intothe air stream. It is intended, that the liquid shall be distributed ina fine thin layer over the surface 9 and glide down this surface in thedirection of the air stream until it leaves the sharp edge 10 of thering in a fine veil in the direction of the air stream. The sharp edgesof the oblique holes 8 aid in thinning and breaking the thin layer ofliquid.

The air. stream is also controlled by guide vanes 11, 12 and 13 whichmay be randomly disposed but for simplicity are disposed in concentriclayers, so that suitable and controlled turbulence and eddy-formation isachieved in the air stream, to increase droplet formation and break-upby relative scrubbing action and movement against the wetted surfacesand hole edges. For the same purpose the ring 4 is bevelled at theoutlet edge 10, this being substantially knife-sharp. The inner andouter air streams from the guide vanes 11 and 12 are thus well mixedwith each other and the liquid leaves the sharp edge 10 in the form of auniform veil which is easily dispersed and distributed completelyhomogenously in the air stream.

Holes 14, drilled through the outer chamber wall on the outside of thering 4 guide liquid in spray against the inside surface 15 of the extraring 5. This ring 5 is also bevelled towards its front sharp edge 16,thus ensuring satisfactory and uniform dispersal of the liquid veil fromthat edge also of ring 15.

The surface 9 of inner ring 4 is designated as a primary distributionsurface, whereas the surface 15 of ring 5 is designated as a secondarydistribution surface. An extra secondary distribution surface 17 isindicated in broken lines, as formed by a tube inside the ring 4, toshow how additional distributing surface area may be provided, ifdesired. in that case, some of the holes 8 could be effectively directedtowards the secondary surface 17, while others are directed tangentiallytowards the primary surface 9, as previously noted.

FIG. 2 shows how yet another secondarysurface may be arranged. For thesake of simplicity FIG. 2 shows only one half of the atomizing device 3.Between the outer ring 5 and the casing 2 is an additional ring 20, theinner surface 21 of which is sprayed with liquid from holes 19 in thering 4. In order to make room for the holes 19, the holes 14, ring 5 andguide vanes 12 have been displaced to the right. An extra set of guidevanes 18 is shown provided for the ring 20.

Where desired, instead of the ring 20, or outside this, a second oradditional hollow ring, like the basic inner ring 4, may be arranged,having its liquid supply and perforated chamber walls as the inner andouter sides. It is possible in this way to continue with primary and Fora given quantity of air, a given quantity of liquid,

i.e. concentration of liquid in the air, and a given flow crosssection,the number or rings and their diameter may be provided so that thedesired mixing ratio can be achieved with desired atomization.

7 By providing an expansion chamber immediately beyond the atomizingregion, increased homogeneity of 1 the mixture is obtained.

The structure may be modified in dimension and arrangement withoutdeparting from the spirit and scope of the invention as defined in theclaims, as for example, forming the main cylinder as a conical structuretruncated at the front apex end.

What is claimed is:

1. Atomizing apparatus for finely distributing a liquid into an airstream, comprising: a. at least one primary, cylindrical tubularstructure defining an open ended passage and having its inner and outersurfaces exposed to the air stream,

said tubular structure having a cylindrical inner surface and an outersurface having an upstream a cylindrical part and a downstream conicalpart forming together with said inner surface a sharp downstream edge,said tubular structure embodying a hollow chamber between said inner andouter surfaces with perforations in the walls of said chamber, saidperforations leading to the inner surface of the tubular structure, andserving to conduct liquid from said chamber onto said inner surface, anddistributing said liquid onto said inner surface;

b. and means for propelling an air stream through said passage and alongsaid tubular structure, to pick up and entrain minute liquid droplets atthe downstream edge of said surface.

2. Atomizing apparatus as claimed in claim 1, having at least onesecondary tubular structure arranged coaxially with said primary tubularstructure, said secondary structure also having a sharp downstream edgeformed by a cylindrical surface facing said primary tubular structureand a conical surface part facing away from said primary tubularstructure, further perforations in the wall of said primary structurearranged for directing jets of liquid onto the said cylindrical surfaceof the secondary structure.

3. Atomizing apparatus, as in claim 2, including, further, means forintroducing fluid into said hollow chamber to travel through saidperforations.

4. Atomizing apparatus, as in claim 3, in which said fluid introducingmeans include a pressure pump. 5. Atomizing apparatus, as in claim 3,including, further,

means for creating turbulence in said air stream to increase theentraining activity of said air stream. 6. Atomizing apparatus, as inclaim 5, in which said turbulence means include guide vanes to modulatethe directional flow of portions of said air said perforations areinclined to be closely tangential to said inner surface of said tubularstructure. 7. Atomizing apparatus, as in claim 3, in which stre amUNITED STATES PATENT OFFICE CERTIFEQATE 0F CORRECTIQN Patent No. 5 917173 Date November 1. 1975 lnvent fl Ritindar S1 ngh It is certified thaterror appears in the above-identified patent and that said LettersPatent are hereby corrected as shown below:

[50] Foreign Application Priority Data April 21, 1972 Sweden. o5252/1972 Signed and gealed this first Day of June1976 [SEAL] A ms 1.-

nu'm c. msou v c. MARSHALL DANN Altesn'ng Officer Commissioner uflanmsand Trademarks

1. Atomizing apparatus for finely distributing a liquid into an airstream, comprising: a. at least one primary, cylindrical tubularstructure defining an open ended passage and having its inner and outersurfaces exposed to the air stream, said tubular structure having acylindrical inner surface and an outer surface having an upstreamcylindrical part and a downstream conical part forming together withsaid inner surface a sharp downstream edge, said tubular structureembodying a hollow chamber between said inner and outer surfaces withperforations in the walls of said chamber, said perforations leading tothe inner surface of the tubular structure, and serving to conductliquid from said chamber onto said inner surface, and distributing saidliquid onto said inner surface; b. and means for propelling an airstream through said passage and along said tubular structure, to pick upand entrain minute liquid droplets at the downstream edge of saidsurface.
 2. Atomizing apparatus as claimed in claim 1, having at leastone secondary tubular structure arranged coaxially with said primarytubular structure, said secondary structure also having a sharpdownstream edge formed by a cylindrical surface facing said primarytubular structure and a conical surface part facing away from saidprimary tubular structure, further perforations in the wall of saidprimary structure arranged for directing jets of liquid onto the saidcylindrical surface of the secondary structure.
 3. Atomizing apparatus,as in claim 2, including, further, means for introducing fluid into saidhollow chamber to travel through said perforations.
 4. Atomizingapparatus, as in claim 3, in which said fluid introducing means includea pressure pump.
 5. Atomizing apparatus, as in claim 3, including,further, means for creating turbulence in said air stream to increasethe entraining activity of said air stream.
 6. Atomizing apparatus, asin claim 5, in which said turbulence means include guide vanes tomodulate the directional flow of portions of said air stream. 7.Atomizing apparatus, as in claim 3, in which said perforations areinclined to be closely tangential to said inner surface of said tubularstructure.